1. Field of the Invention
The present invention relates to the area of photo-film units. More particularly, the invention relates to a masking material for a photo-film unit having a writable area, and a photo-film unit having a writable non-image portion provided on the surface on the image viewing side, using the above-mentioned masking material.
2. Description of the Related Art
There has conventionally been known a mono-sheet type instant photo-film unit. About ten sheets of this film unit are housed one on top of the other in a cartridge and set in a photographing equipment such as a camera. Immediately after photographing, the units are released one by one from the photographing equipment through a pair of rollers. Upon passing between the rollers, a pod provided on each film unit is broken. The developing solution contained in the pod is dispersed over a photosensitive layer for development, thus giving a photo. According to the mono-sheet type instant photo-film unit, it is not necessary to carry out stripping operation after the completion of development. The mono-sheet type instant photo is described in detail in the U.S. Pat. Nos. 3,415,644 and 3,954,476, and Japanese Unexamined Patent Publications Nos. 50-153628 and 48-43317, and is typically represented by Spectra System of Polaroid Corporation, and ACE System and Instax System of Fuji Photo Film Co., Ltd.
Mono-sheet type instant photos are broadly classified into a type (used in Spectra System) having a structure in which a positive photosensitive material sheet and a negative photosensitive material sheet are placed one on top of the other as separate supports into a lamination, and a post-shooting developing solution (having temporarily light shielding property, and then becoming white) can be injected between the sheets, and another type (used in ACE or Instax) having a structure in which a positive photosensitive material and a negative photosensitive material are held on the same support, and a post-shooting developing solution (having a light shielding property) can be injected between a cover sheet and the thus formed combined layer.
The latter type is further divided into an outside mask type (Instax) in which a mask material serving as a frame determining an image forming area of a photo is located outside (above) the photosensitive material, and an inside mask type (ACE) in which a masking material is located inside (below) the photosensitive layer. The type in which the positive photosensitive material and the negative photosensitive material are on separate supports is based on the outside masking method in principle.
In any of the several above-mentioned types of mono-sheet type instant photos, a complete image is available on the spot, providing a remarkable advantage of convenience. Furthermore, it would be very convenient if the user can fill in on the spot information about the object of photo, the date of shooting, the photographer, a message and other supplemental information on the resultant photo, it is the usual practice to retain an area in an photo-film unit imparted writability in a non-image portion on the image viewing side.
In general, in order to impart writability to the non-image portion, a mat material such as silica dispersed in a non-polarity binder is coated onto a polymer film supporting the non-image portion. By thus forming a mat layer on the non-image portion, writability with a ballpoint pen or a pencil can be provided, but with an aqueous writing material, ink is repelled, and writability is denied to this extent.
Trials to impart an excellent writability including aqueous writing material include a method of coating a mat material dispersed in a hydrophilic resin such as polyvinyl alcohol or gelatine onto the support of the non-image portion is disclosed in Japanese Unexamined Patent Publication No. 55-17124. In this method, however, when water drops drop onto the writability imparting layer or t he layer is dipped into water, a problem is caused in that writability of the portion in contact with water is reduced or even disappears.
As means to solve this problem, Japanese Unexamined Patent Publication No. 57-152949 discloses a method of providing a writability imparting layer comprising a saponification product of a porous ethylene-vinyl acetate copolymer having a rough surface on a plastic film. However, the writability imparting layer available from this method has fine pores throughout the length and breadth. Because, after writing with an aqueous writing material, blurs occur before the layer is dried up, this method is not suitable for writing fine characters with an aqueous writing material. While pencil-writability is satisfactory, a low rubber erasability of pencil-written images is a problem.
The present invention was developed in view of the aforementioned problems, and has a first object to provide a method of imparting writability to a photo-film unit for any of the commonly used writing materials such as a ballpoint pen, an oily pen, an aqueous pen, a fountain pen and a pencil.
A second object of the invention is to provide a writability imparting layer which exhibits excellent writability for all the commonly used writing materials, is water-resistant, and permits complete erasion of pencil writing with an eraser without the risk of blocking.
To achieve the aforementioned objects, the invention provides a mask material for a photo-film unit having a writability imparting layer comprising vinylpyrrolidone-vinyl acetate copolymer, an acryl resin having a hydrophilic group, and a powder as an outermost surface layer formed on a support film.
This writability imparting layer has no blurs or patchiness even when using an aqueous writing material or a fountain pen under the effect of hygroscopicity of the vinylpyrrolidone-vinyl acetate copolymer, and exhibits satisfactory writability. The writability imparting layer ensures impartation of water resistance without impairing hygroscopicity of vinylpyrrolidone-vinyl acetate copolymer by the addition of an acrylic resin having a hydrophilic group. Pencil-writability is imparted to this writability imparting layer by the addition of powder so as to permit complete erasion of even pencil writing. This writability imparting layer is hardly susceptible to blocking.
In a preferred embodiment, the photo-film unit masking material of the invention has a writable area comprising at least a lamination of a primer layer a), a white layer b), and as an outermost surface layer c) the aforementioned writability imparting layer formed in this sequence on the aforementioned support film. In another preferred embodiment of the photo-film unit masking material of the invention, the primer layer a) comprises a hardened (cured) composition containing acrylpolyol, vinyl chloride-vinyl acetate copolymer, polyfunctional isocyanate, and a white pigment. In another preferred embodiment of the photo-film unit masking material of the invention, the white layer b) comprises a hardened (cured) composition containing urethane, polyfunctional isocyanate and a white pigment. In still another preferred embodiment of the photo-film unit masking material of the invention, a white layer bxe2x80x2) comprises a hardened (cured) composition containing urethane, acrylpolyol, vinyl chloride-vinyl acetate copolymer, polyfunctional isocyanate, and a white pigment.
Furthermore, the invention provides a photo-film having a matting material having the aforementioned writability imparting layer provided on a non-image portion in the same plane as the image portion of the photo-film unit.
In further another preferred embodiment, the photo-film unit of the invention has a writable area comprising at least a primer layer a) comprising a hardened composition containing acrylpolyol, vinyl chloride-vinyl acetate copolymer, polyfunctional isocyanate and a white pigment, a white layer b) comprising a hardened composition containing urethane, polyfunctional isocyanate, or a white layer bxe2x80x2) comprising a hardened composition containing urethane, acrylporryol, vinyl chloride-vinyl acetate copolymer, polyfunctional isocyanate and a white pigment, and a writability imparting layer serving as an outermost surface layer c), laminated in this sequence.
In these embodiments, the aforementioned white layer b) or white layer bxe2x80x2) containing a white pigment is formed under the writability imparting layer. Because even a thick white layer b) or bxe2x80x2) does not cause a curl, it is possible to impart a sufficient white concealing property to the writable area.
The aforementioned white layer b) and white layer bxe2x80x2), while exhibiting a sufficient white concealing property, are low in adhesion to a support film. The above-mentioned primer layer is therefore provided between the support film and the white layer b) or bxe2x80x2). This primer layer, containing a white pigment blended therein, contributes to improvement of white concealing property of the writable area.
The writable area provided in the masking material of the present invention is water-resistant, and exhibits an excellent writability for all the usually used writing materials including a ballpoint pen, an oily pen, an aqueous pen, a fountain pen, and a pencil. Even a pencil writing can be completely erased with a rubber. Using such a masking material, it is possible to manufacture a photo-film unit having a writable non-image portion.
As compared with the white layer composition forming the white layer b), the white layer composition forming the white layer bxe2x80x2) additionally contains acrylpolyol and vinyl chloride-vinyl acetate copolymer. Elongation of the white layer bxe2x80x2) formed by such a white layer composition is further inhibited. The masking material having such a white layer bxe2x80x2) formed thereon has an excellent fabricability and is suitably applicable to a processing process of a photo-film unit, because application of additional tension or the like to the masking material during processing in the manufacture of a photo-film unit further inhibits elongation of the white layer bxe2x80x2).
The same writability imparting layer as that of the above-mentioned masking material is provided in the non-image portion of the photo-film unit of the invention, it is water-resistant, shows an excellent writability for all the usually used writing materials such as a ballpoint pen, an oily pen, an aqueous pen, a fountain pen, and a pencil, and permits complete erasion of even pencil writing with a rubber. Since the writable area (area in which the writability imparting layer is formed) portion of the photo-film unit of the invention is hardly susceptible to blocking, a plurality of photo-film units, if housed in a cartridge, can be smoothly drawn out one by one.